Grinding machine



June 13, 1939. w. .J. wlLsoN GRINDING MACHINE s sheets-sheet 1 Filed Sept. l5, 1938 .N VE,

June 13, 1939.

wl J. wlLsoN 2,162,044

GRINDING MACHINE Filed Sep?. 15, 1938 3 Shee'l'fS-Shee'by 2 me/who@ Wf/.Wizm

June 13, 1939. WI J. MLSON 2,162,044

GRINDING MACHINE fr, "d j i ,g

WJ. /Vlaozz Patented June 13, 1939 UNITED STATES PATENT OFFICE 15 Claims.

'I'his invention relates to grinding and shaping apparatus and pertains particularly .to apparatus for grinding .occlu'sal surfaces of posterior teeth. In the manufacture of dentures, extreme diiiiculty is experienced in producing a set of dentures because of the fact that there are not supplied by the manufacturers the proper materials of correct design which enables a dentist to make the dentures so that the oc'clusal surfaces of the teeth will come together in such a manner as to conform to the movements of the jaws, and it has been my conclusion that the dentist must start with the tooth design and manufacture the saine so that the upper and lower occlusal surfaces of the teeth of a particular set will be matched .and thus `will conform to the motions of the jaws after they have been placed in a patients mouth, thereby obtaining the correct action for the process of mastication 20 and avoiding movement or ytipping of the dentures such as commonly occurs in dentures constructed according to the present methods.

The present invention has for its primary object to provide an apparatus upon which maybe cut models for upper and lower blocks of posterior teeth, accurately designed so Vthat they will have interengaging or interlocking cusps which when cast in porcelain for mounting in dentures, will provide upper and lower posterior teeth Iwhich are accurately matched so as to vconform -to 'the motions of the jaws ofthe person wearing them.

Another object of the invention vis to provide a grinding apparatus by means of which upper and lower posterior teeth may be produced hav- 5 ing elliptic concave and convex surfaces of cusps formed on a curved outline which interlock, upper with lower, and permit an elliptic movement of the jaw, which :is the natural Vmovement which the jaw has during the process of mastication.

Still another object of the invention is `to provide a grinding apparatus which is designed to facilitate the cutting of models for posterior teeth in which the cusps have elliptic concave and convex surfaces and having means whereby the porcelain tooth or block of teeth after being made from the model and fired, maybe set back in the grinding apparatus `in exactly the `same position as that previously occupied by the model and 50 have the curved cusp surfaces reground to the original form to overcome distortions produced in the porcelain through the firing process.

Still another object of the invention is to provide in a grinding apparatus of the character hereinafter set forth, a -novel means for moving a body along certain predetermined curved paths with respect to a grinding wheel whereby a desired grinding action .is obtained.

vA further object of the invention is to provide in a machine designed to facilitate the grinding of a body as `above described, a means whereby the grinding operation may -be carried out with respect `to two bodies which .are intended to work together, so that such :bodies will have eoacting cusps accurately matched to interlock for coacting grinding relation.

A further importantobject lof the invention is to provide a tooth grinding apparatus by which may -be produced upper and lower posterior teeth or blocks Vof 'such teeth having elliptic concave .and 'convex surfaces of `cusps on a curved outline which interlock and permit an elliptic .movement of the Jaw as may be readily demonstrated 'upon an articulator such, for example, as the articulator forming the subject-matter of my co- 4pending application filed of even date herewith, with the centers of the radii of all of the curves in fthe central median line plane, by which is mea-nt an imaginary -plane extending through thehead and neck from the front to the back on the exact center rdividing the body into two equal parts.

The invention Will lbe .best understood from a :consideration -of the following detailed description taken in connection with the accompanying drawirlgs .formi-ng part of this specification, with the understanding, however, that the invention is not to be .confined to any strict conformity with the showing of the drawings but may be changed or modified so long as suchV changes or modications mark no material departure from the salient features of the invention as expressed in the appended claims.

In the .drawing-s:

Fig. 1 is a View in .front elevation of the grinding -apparatus embodying the present invention.

Fig. `2 `is `a view in side elevation of the same.

Fig. 3 is a View in top plan of the apparatus.

Fig. 4 is a sectional view taken substantially on the line 4-4 of Fig. 3,

Fig. 5 is a view of one form of modeling block 'carrying ,-frame.

Fig. 6 is a sectional View on the line 6-6 of Fig. 3.

Fig. '7 is a sectional View on the line 'l-'I of Fig. 3.

Fig. .-'8 is a sectional view `on the line 8-8 of Fig. 7.

Referring now more particularly to the drawings, the numeral I generally designates a supporting base for the apparatus upon the top of which is formed, adjacent the edge which may be referred to as the rear edge of the base, the block 2 having .a dove-tail slot 3 therein extending from front to rear. Upon the base block 2 is a carriage block 4 having upon its underface a dovetail rib 5 slidably engaged in the slot 3. Upon the top of the carriage 4 is secured the vertical housing or standard 6 upon the upper end of which is a gear casing 1 through which extends a shaft 8. Within the casing 1 are suitable gears coupling the shaft 8 with a suitable driving shaft which is preferably of the exible type and which is not shown but is carried upwardly through the standard 6 in a suitable manner to transmit power to the shaft 8. Upon one end of the shaft 8 is a grinding wheel or disk 9.

Suitable means is provided for constantly urging the grinding Wheel forwardly with respect to apiece of work, such as a spring I0 coupled at one end with a pin I| which is joined to the carriage 4 and at its other end to a stationary attaching means I2 secured to the base In orderY that the operator of the apparatus may be able to shift the carriage 4 and thegrinding wheel away from him and` away from the work when necessary, there is provided the oscillatable lever I3 suitably pivotally supported intermediate its ends in the base block 2, as indicated at |4, and extending upwardly through a suitable recess in the carriage 4 to a point above the ytop of the carriage while its lower end extends below the base plate I and is provided with means, such as the eye I5, for the attachment of an actuating rod I6 thereto.4 The rod I6 is carried forwardly and has its other end connected with one end of a lever I1 which is pivotally supported upon the underside of the base by means of spaced ears |B as shown.

The carriage 4 carries at its rear edge a bracket I9 having a threaded passage therethrough for the reception of an adjusting screw 20 which extends toward the front of the apparatus and is designed to be shifted longitudinally thereof and the forward end of this screw is engaged by the upper end of the oscillatable lever I3. Thus it will be seen that when the operator of the apparatus oscillates the Ycrank lever I1 to pull the link bar I6 forwardly, the lever I3 will bear against the screw 20 and force the carriage rearwardly against the tension of the spring II).

The forward movement of the carriage is Vlimited by the rearwardly directed screw 2| which is threaded through the passage in a bracket 22 mounted upon the base I.

Upon the base I in front of the grinding wheel supporting carriage 4, there is formed the block 23 which is provided with a dove-tail slot 24 extending transversely of its top face or, in other words, extending across the base I perpendicular to the dove-tail slot 3 in which the carriage 4 slides. Upon the block 23 is a pivot post block 25 having a dove-tail rib 26 engaging in the dovetail slot 24 and carrying the vertically extending tubular post 21 which terminates at its upper end Yin the horizontal circular plate 28.

'I'he hollow central portion 29 of the post 21 passes through the plate 28, as shown in Fig. 4, andreceives a pivot post 39, the upper vend of which is formed integral with a disk 3l which rests upon and is concentric with the disk 28. An operating screw 32 is swivelly supported in a bracket 33 upon the base I and has threaded connection with the pivot post supporting plate 25, so that by means of this screw, the plate 25 and the structure supported thereby may be moved transversely of the base I and consequently with respect to the grindingedge of the disk 9.

The forward edge of the non-rotatable disk 28 has set out thereon a scale 34 indicating degrees of a circle, starting at a zero point which lies in a vertical plane passing longitudinally through the apparatus or from the front to the rear thereof and through the thickness center of the grinding wheel 9, and the upper or rotatable platev 3| has a suitable centering mark thereon,

1 as indicated at 35 by which certain degrees of oscillation of the plate 3| and the structure which it carries, as hereinafter described, may be determined.

The rotatable plate 3| carries and preferably has formed integral therewith, a block or headpiece 36 which is provided in its top surface with a dove-tail slot 31 which extends longitudinally of the apparatus perpendicular to the slot 24. This head-piece forming a part of the rotatable disk 3| is slidably coupled with the body 38 which Yis formed upon the underside of an elongated table bar 39 at the transverse center of the latter and has a dove-tail rib 40 engaging in the slot 31. A bracket 4I carried by the rotatable disk or plate 3| supports an adjusting screw 42 which is engaged in a suitable threaded passage in the table bar block 38 and by this screw backward and forward movement of the block and table is Lying upon the top surface of the table bar Y and extending longitudinally thereof is a rack bar 46, the teeth of which are in mesh with the gears 45, as shown in Fig. 4, the rack bar being maintained in position with respect to the gears and held for sliding movement on the table bai` 39, by suitable guides 41, which are secured to the table bar, as shown.

At a slight elevation above the table bar 39, each of the posts 44 is slightly reduced in diameter, as shown more distinctly in Fig. 7, to form a shoulder 48 and this upper reduced portion of each post is indicated by the numeral 49 and, as shown in Fig. 8, is provided with four longitudinally extending slots 50 which are equi-distantly spaced around the post.

Secured in the slots 59 of each post are guide plates 5|, 52, 53 and 54, the guide plates 5| and 52 having their vertical edges concave while the plates 53 and 54 have their vertical edges convex, and it will be noted that a plate 5I is spaced 180 from a plate 53 and that the machine when set up for use has a plate 5| of one post in edge opposed relation with a plate 53 of the opposite post. These plates are held in position in their respective slot-s by and between collars 55 encircling the reduced portion 49 at the upper and lower ends thereof and a nut 56 threaded upon the upper end of each post and bearing against the upper collar.

The numeral 51 generally designatesahandunit which is used in connection with the other parts sists of a frame formed of a relatively long-'piece of bar materialand sha-pe to provide 1a central portion 58 connected with and offsetfrom oppo- 'sitely directed termina-l portions 59 Eby the intermediate langularportions 60. 'The 'terminal `.por- -tions -of A'the frame 'far-e, through-'a portion `of their length, of circular cross-section toform trunnions .6l upon each of which is aguide'blockfGZ 'having a 'concave YVface '63 and fa convex face 1T64. The curvature of' these faces :163 44andll correspond with the curvatures of theedges ofthe 'plates 153 and'fl.

Inwardly 'of each of th'e2blocks'62,the terminal portion 59 -Ioi? the hand unit'is Iprovided with a suitable aperture to 'receive "the eccentrically arranged threaded 4'stud'lS extending from the lend .one 'post to the other, sothat fthe blocks 62 may be 'positioned against the edges -o'f certain 'of the plates carried bythe posts Aand the distance between the remote sides ofthe pins 6l is `'such 'that these pins will engage the opposed edges of the inner ones -of the guide plates-as shown in Fig. 3.

The o'iset portion v"58 of the vhand -unit vhas positioned 'against the inner side thereof' one of two modeling block carrying frames, one of `the frames being vindicated'generallyby the numeral 651Whileth'e otherframe, shown vin -detail in'Fig. 5, is indicated general-1y by the numeral 66. The frame `65, which is shown assembled with the 'hand unit, 'consists of a back 'bar I61 which is designed to lposition'a-ga'inst -the forward face of 'the offset portion 5518, and 'a convex front bar which is longitudinallyslotted. 'The back bar carries the 'threaded stud `652 'which 4extends throug'han opening 'HJ in the oiset portion 58 to receive a clamping .nut ITI. By this means the frame S5 is held in adjusted position upon the hand unit.

The -numeral '1x2 Idesignates -a Y'shoe which is shaped upon one side .to position against the convexface -of lthefront bar18 and the vopposie face of this shoe is provided with a suitable means, such las the Ychannel '73, for -holding -a modeling block such as is indicated `yby thenurneral '14 `in Fig. 4.

Extending from vthe -rear `side of the shoe 12 is a threaded stud '.'5 which passes through the slot of the front bar'l68 and has threaded thereon the securing screw `'(6.

'One side of the yshoe TZ carriesan index tooth A'Vl which is designed for engagement with the notches formed along the 'edge vof an index bar *I8 which is secured to `one side of the bar 63, as shown in Fig. A3.

The frame isemployed-during -the modeling of an upper Lblock of posterior teeth. For the modeling of a'lower block, the frame 65 is used and this frame, like the frame ('fhas a back 'bar 19 and a front bar im, which vis longitudinally Vslotted Abut the front b'ar is of 'concave form and the shoe 8l, which is secured to the concave face thereof, Vhas a convex back surface to conform to the-concaveform of `thebar 86 against which it is held bythe nut 182 which is threaded upon 'the stud 83 which passes lthroughthe slot of the bar i189 fromth'e shoe L8l. This 'shoe 8| carries anindexlt'oothi84 for `coaction with a notched findexlplatefo'f the same type as the :plate i158,

`except that it is concave torconform "to the bar aB0 instead -of convex.

The disk 28 has secured thereto a vertically disposed bracket s'leevei86. Extending dacross the upper end of this sleeve isa horizontal slotted guide bar l8l. The slot "88 of this bar extends across a slot 89 which vis formed in and longitudinally `of the table bar Z39 at .one side of the transverse center thereof, as vshown in Fig. -3. The slotted bar 81 carrier and lhas `securely'iixed thereto the downwardly extending 4pin Eil!) which passes through the sleeve 86, as shown in Fig. 1.

The rack bar-46 has secured .thereto andex- 'tending downwardly therefrom a pin 91 `which passes through the slot 89 in the table :bar :and engages in the slot of the slotted bar 81.

The plates 2i and 38 may be securedagainst relative movement by a suitable clamp :such as is shown in Fig. l Yand indicated by4 the vnumeral 92.

Teeth formed or designed upon the present machine may be made in blocks varying .in meas-- urement from 28 to 36 m. rn. in mesio :distal length. 'The angle o'f the cusps 'may vary Vfrom l0 to 35 and the angle of the blockwith the median line may vary from `to 20 and 'the curvatures may differ anywhere 'from 3 to 6". All of these variables dueto the size of the teeth are taken care of in the several adjustments which may be made in the grinding machine or a change in the guides and guide blocks or shoes. -It'might be said that a 30 or 32 in. m. block with the 'teeth ground by using guide plates 5-I and 53 having a Ll radius edge and guide platesl52 and 54 having a 5" radius edge would be called medium and:

could be used in a great majority of cases and also in the majority of cases the blocks whenset inthe patients mouth would makeapproximately a 1'71/2o angle with the median line, although this angle might vary with the size of tooth and size# of the mouth.

The guide frame 65, or the `frame 66 when it is mounted upon the unit i5'l, is vadjustable to any angle for obtaining the Vapproximate angle between a block of teeth, composed of the bcuspids and molars and the zmedian line. 'Ihis adjustment is obtained by the-use of the Vscale 93 formed on the face of the Ahand-piece '5l at 'the forward edge of the opening 64 which is concentric with the center of the frame 65 or the screw 69. The bar portion 61 of the frame 65 has an index point ithereon` which is viewable through the aperture 194 for use in `association with the scale. This adjustment is for right and left sides of the stud and nut 67-11 hold the guide frame in position on the oiset portion 56 of the hand-piece or hand unit. Theguide pins '64 engaging the edges of the vertical guide plates 5|53 keep the work centered with respect to the grinding wheel and impart a slight curved,y

movement which is incorporated in the curvature of the cusps, when the hand unit is moved up and down while maintaining the blocks 62 in sliding engagement with the guide plates- 5l. As will be readily seen upon reference to Figs. 1 and 2, the guide plates are used in pairs set 180 apart or directly opposite and the guide plates 15I and 53 have the same 4" radius while the other guide plates 52 and 5t have a 5" radius and are set on the shafts at from the 4 radii guides 52-54.

The frame of the hand unit has Abeen shown 4in position with the blocks 62 in Contact with the vertical guide plates 5i. rIhe `guide pins 64 `are sho-wnengagedagainst the inner .guide plates? The modeling block 14 is held in the removable support or holder 13 which is detachably slidably connected with the shoe 12. This shoe 12 can bemoved and indexed, by means of the tooth 11 and plate 18, along the curved forward bar 68 of the frame 65. This bar or convex portion 68 of the frame has' a radius smaller than 5 to compensate for the distance from the wheel. In the case of the concave bar of 1 l: the frame 66, which is used for forming the lower teeth, the radius of the bar 80 is greater by the same distance. Y

The illustrations o-f the machine show the latter in what might be termed the neutral position, in which the table 39 is perpendicular to the central plane of the grinding wheel 9 and it is from this position that the necessary adjustments are made for beginning the grinding of a block of teeth. Starting with the machine table in this position, a straight edge is placed across the guides 5| and the central point between the guides is marked thereon and the lower screw 32 is then vemployed for bringing this center into coincidence with the plane of the center of the grinding wheel. The wheel or stone is then backed away from the table by operating the lever l1 and the carriage o-r table is then rotated to an angle of approximately 25 with'respect to the plane of the wheel, this angle being obtained by the use of the scale 34 and the marker 35. The screw 42 is then operated to move the carriage or table 39 on the block 36 away from the stone or wheel and at a 25 angle to such a point found by trial that when the stone is advanced, the edge will hit the center marked on the straight edge. While these adjustments are being made, vthe pin 9| which communicates motion to the rack 46 will be removed and is not put back into position until the table 39 is at the 25 position referred to and the above described adjustments have been made and the Ymember 81 is then adjusted with reference to the pin in such a manner that the correct position of the guides 5| will be maintained through the rack and pinions 45 and 46 which govern the rotation of the standards 44. This adjustment of the member 81 will then be such that the members 44 will be rotated through when the table 39 is rotated to 25 on the opposite side of the center of the grinding wheel. This action changes the position of all guides and brings guides 53 into operating position in place of the guides 5| or vice versa, and when the adjustments are properly made, the opposite edge of the wheel will hitthe central point located by the straight edge when the table is rotated as described. After making these preliminary adjustments, a modeling block such, for example, as the block 14, is secured in place in a holder 13 by the use of a suitable modeling compound and the holder is then placed in the shoe 12. The frame 65 will be set to the desired operating angle, such, for example, as the 171/2 angle described and then if the left side of the Y table 39 has been swung toward the grindingwheel to the operating position of 25 with the plane of the wheel, and an up and down movement be lgiven to the hand-piece with the blocks 62 in contact with the guides 5I and with the pins 64 in contact with the guides 52 and 54, such an arcuate movement will be described by the modeling block with reference to the revolving grinding wheel that an upper distal convex surface of a cusp will be formed. The shoe will be given the necessary adjustments along the bar 68 as designed by the index plate 18 until all of the parallel cuts have been made in the block.

When the carriage or table 39 is then rotated with the right hand side thereof towards the wheel and to a 25 angle opposite from its first position, the standards 44 will be rotatedthrough 180 through the mechanical connection of the rack and pinions between them and the table, thus bringing the guides 53 into working position for engagement by the blocks 62. 'I'he shoes or blocks 62 will then be turned over to present their concave surfaces to the convex guides 53 and with the guide pins 64 in position against guides 54 and 52 whichhave also been changed when the shafts 44 rotated, the up and down movement of the hand piece in the same manner as previously described, will import such an arcuate movement to the modeling block with respect to the grinding wheel that an upper mesial concave surface of a tooth cusp will be formed.l

These arcuate cusp surfaces have one definite curve produced bythe guides 5| and 53 which have a 4" radius as previously stated.

The pins 64 have been described as operating to keep the work centered and impart a slight curved movement to the hand unit which gives a curvature to the cuspsl By forming the threaded studs 63 of these pins eccentrically as previously described, provision is made for a retruded bite, which the normal jaw with the natural teeth in place makes. Provision for this retruded movement of the lower jaw must be made in the design of the artificial teeth by giving a slight clearance between the lower distal half of each cusp and the upper mesial half of each upper cusp. By retruded bite is meant a clearance between the upper and lower cusps of the teeth which permits the jawy to move distally a definite amount, which may approximate .02. Because of the angular operating position of the guides with respect tol the stone, the necessary adjust-Y ment cannot be made by the movement of the block 25 on the bodly 23, therefore, the guide pins 64 are made eccentric and by rotating the pin 64 through 180, the hand piece is set over one-half of the desired clearance for the retruded movement and clearance, the other half of this clearance being ground from the opposing block of teeth.

After forming the cusps in the manner described, the block is removed and is hand-carved for the esthetics of the case, but the main outlines of the ground surfaces are preserved. A mold is then made from this model and the porcelain is cast or shaped in the mold. This molded or shapedporcelain body is then fired and since the firing operation causes the porcelain to shrink, this shrinkage is taken care of by using two sets of index plates, o-ne for the model and one for the finished porcelain, After annealing, the porcelain block of teeth is accurately located in the holder 13 by a jig and is lightly ground to conform to the size called for by the index plate. A set of index plates consists of an upper and lower, one each for the pattern and one each for finish. With accurate index plates and a properly constructed machine, all teeth of the same design and measurements will articulate and fit perfectly. The index plates are made so that the upper and lower cusps interlock. The formation of the cusps are the same in upper and lower, right or left, and at the same predetermined angle with the occlusal plane in each particular design. The angle of the block with the median line is the same, but the occlusal curva- 7 lil) tureof the upper is convex and of the lower is1 concave.

What is claimed iszl y 1. Agrinding machine. ofi the` character: de.- scribed, comprising. a rotatable. grinding disk, a carrier for a, body. to., be groundagainsttheedge. of said disk, means forming. a pair; of. vertically. spaced guides adjacent .the diskv and; .disposeiat opposite sides of. the, vertical plane of: the sama, and means formingf a. part of said carrierfortsild.- ing contact with said guides, saidguides beingso constructed and arranged thatthe. carrier when moved vertically. along thesame. will moveth'e. said body in a vertical. arcuate pathagainstthe edge of said disk and in a curvedipatlr ina.. plane perpendicular to the; arcuate p ath.,

2. A grinding machine'for modeling. cuspsrfor articial posterior teeth, comprising, a rotary grinding disk, a pair of standards disposed upon opposite sides of the. vertical plane of. said. disk, a vertical. guide plate carried. byeachstandard; and having a longitudinally. curved edgev form, a manually actuated unit formed. to extend across. and connectA said standardsfand havingportions; for slidable engagementwith the edges of. said. guide plates, means carried. by said-,unit forsupporting a body in position for contactVv with thev edge or" said disk, and said plateshavingvertically extending edges curved to effect the. move..- ment of said body inan arcuate path .with respect to said disk edge when .the unitisv moved;- vertically in contact with the plates.

3. A grinding machine for modelingi cusps. for artificial posterior teeth, comprising; a. rotary grinding disk, a pair of standards disposed; upon opposite sides of the vertical plane. of said disk, a vertical guide plate carriedby each standard .andy having a longitudinally curved edgeiform, a manually actuated unit formed.` to extend across and connect said standards. andhaving portions for slidable engagement; withv the,` edges. of .said guide plates, meanscarried bysaid unitlfor. supe porting a body in position for contactwiththe edge of saidl disk, said plates havingvertically excnding edges curved to effect.; the.` movement vof said'body in an arcuate path with. respect. to;said disk edge when the unit is moved1vert'icallyv in contact with the plates, and means supporting the standards facilitating disposing the samein a common vertical planeV extending. across the edge of andv obliquely of the plane of. said disk.

4. A grinding machine for modeling-f cuspse for articial posterior teeth, comprising. a rotary grinding disk, a table pivotally supported adjacent the edge of said disk with its pivotal center dis,- posed vertically and in theverticalplaneof the disk, a pair of standards carried by andi rotatable on the tableand disposed upon oppositesides of said center, guide elements carried by andfextend.- ing longitudinally of said standards abovethe table, said guide elements having longitudinally curved outwardly directed edges, a framemember adapted to extend across said standards; means carried by said frame for sliding contact with the curvededges of certain of the platestcarried by said standards whereby said frame. when moved vertically Iwill be guided in a Verticalarcu.- ate path, and means carriedy by saidirame.` for supporting a modeling blockV in positionV for. en gagement with the edge ofsaid grinding disk..

5. A grinding machine for modelingfcusps for articial posterior teeth, comprising; a`v rotary grindingdisk, a table pivotallysupported adjacent the edge of said'diskwith its. pivotal center, dis.- posed vertically and. in.. the verticalplaneioirthe disk, a pair of standards carried by and rotatable on the table and disposed upon opposite sides of said center, guide elements carried by and extending longitudinally of said standards above the table, saidguide elements having longitudinally curvedoutwardly directed edges, a frame member adapted to extend acrosssaidv standards, means carriedby said frame for sliding contact withv the curved edges of certain of the plates carriedfby said. standards whereby said frame when moved vertically will, be guided in a vertical arcuate path, means carried by said frame for supporting a modelingblock inposition for engagement with the edge of said grindingl disk, and means carriedv by said frame and engaging the curved edges of certain, other ones of the plates of said standards for-imparting anv arcuate movement to the frame as the same is moved vertically opposite to the first-mentioned arcuate movement.

6. A grinding machine for modeling cusps for artificial posterior teeth, comprising a rotary grinding disk, a table pivotally supported adjacent the edge of said disk with its pivotal center disposedvertically and in the Vertical plane of the disk, a pair of standards carried by and rotatable on the. table and disposed upon opposite sides of said. center, guide elements carried by and. extend.- ingflongitudinally of said standards above the table, said .guide elements having longitudinally curved outwardly directed edges, a frame member :1

adapted tor extend across said, standards, means carried by saidframe for sliding contact with the curved edges of. certain of the plates carried. by said, standards whereby said frame when moved vertically will be guided in a. vertical arcuate path, means carried by saidl frame for supporting a modeling block in position for engagement with the edge of`said grinding disk, and means facilif tating the oscillation of said last means. on an axis extending transversely of. the framein the plane; of said disk whereby the said modeling body may be oscillated with respect to the edge of the disk.

7. A grinding machine for modeling cusps for artificial posterior. teeth, comprising a rotary grinding disk. disposed in a vertical plane, atable mounted". for oscillation on a vertical pivot dis,- posed4 in the said plane ofr the disk, means for shifting said table horizontally toward or away from. the disk,.a pair of. standards rotatably vertically supported on the table in. spaced relation and. at opposite sides. of the plane ofthe disk, a plurality of guide plates carried by andextending longitudinally of each standardV above the table,

the disks ofV each standard being divided into two e groups in which one group has longitudinal concave outer edges. and the` otherr group has longitudinal convex outer edges, means. whereby oscillation. of the table to either ofY two. angular positionswith respect. to. the plane ofA said. disk willv dispose platesof corresponding` edge formation. in parallel relation, av framev adapted. to

eXtencLbetween the standards, means carrierV table mounted for oscillation on a vertical pivot disposed in the said plane of the disk, means for shifting said table horizontally toward or away from the disk, a pair of standards rotatably vertically supported on the table in spaced relation and at opposite sides of the plane of the disk, a plurality of guide plates carried by and extending longitudinally of each standard above the table, the disks of each'standard being divided into two groupsv in which one group has longitudinal concave outer edges and the other group has longitudinal convex outer edges, means whereby oscillation of the table to either of two angular positions with respect to the plane of said disk will dispose plates of corresponding edge formation in parallel relation, a frame adapted to extend between the standards, means carried by the frame for sliding contact with the curved edges of the said parallel plates, said frame being designed for vertical movementl against said parallel plates whereby the edge formation of the plates will impart vertical arcuate movement to the frame, means for-securing a modeling body to the frame in position to be contacted by the edge of said disk when the frame is given said vertical movement, and means whereby said last-mentioned means Vmay be oscillated on a horizontal axis disposed in the plane of the disk to arrange the modeling body at a desired angle with respect to the edge of the disk.

9. A grinding machine for modelingcusps for artificial posterior teeth, comprising a rotary grinding disk disposed in a vertical plane, a table arranged horizontally transverselyvof said disk adjacent the edge thereof, supporting means for said table for oscillating the same on a vertical axis disposed in the plane of the disk, means for shifting said table horizontally toward or away from the disk, means for shifting the table horizontally transversely of the disk, a frame unit,v .means carried by the frame unit for supporting a modeling body thereon. for engagement with the edge of said disk, and coacting means between the table and said frame at opposite sides of the plane of said disk for effecting the simultaneous movement of the frame along two separate arcuate paths as the frame is manually moved vertically with the moleding body carried thereby in contact with the edge of the disk. d

10. A grinding machine for modeling cusps for artificial posterior teeth, comprising a rotary grinding disk disposed in a vertical plane, a table arranged horizontally transversely of said disk adjacent theredge thereof, supporting means for said table for oscillating the same on a vertical axis'disposed in theplane of the disk, means for shifting said table horizontally toward or away from the disk, means for shifting the table horizontally transversely of the disk, a frame unit, means carried by the frame unit for supporting a modeling body thereon, for engagement with the edge of said disk, coacting means between Y the table and said frame at opposite sides of the plane of said disk for effecting the simultaneous movement of the frame along two separate arcu- VVate paths as the frame is manually moved vertically with the modeling body carried thereby in contact with the edge of the disk, means whereby the said modeling body may be adjusted with respect to the edge of the disk through oscillation on an axis disposed horizontally in the plane of the disk, and means for shifting the modeling body with respect to the frame in a path transversely of said oscillation axis.

11. A grinding machine Yfor modeling cusps for artificial posterior teeth, comprising a rotary disk disposed in a vertical plane, a table extending transversely of the edge of said disk and mounted for oscillation on a vertical axis lying in said plane, means for shifting said table'in a horizontal path toward and away from the edge of the disk, means for shiftingv the table in a horizontal plane along a lpath perpendicular to said plane, a pair of standards rotatably supported vertically on the table. upon opposite sides of said plane, a plurality of plates carried b-y each standard above the table and extending longitudinally of the standard, the disks of eac-h standard being divided intoV one group having longitudinal concave outer edges and a second group having longitudinal `convex outer edges, a gear carried by each standard, a rack connecting said gears, meansfor Veffecting longitudinal reciprocation of said rack upon oscillation of the table on the said vertical pivot therefor, a frame constructed to extend across and between said standards through the plane of Vthe disk,Y

bodies carried by said frame and each adapted to slidably contact an edge of a plate of a standard, pin members carried by the frame to extend transversely with respect to the standards and each designed for sliding contact with an edge of a plate of a standard, and means carried by the frame for supporting a body in position for contact with said disk edge when said first bodies are contacting their respective standard plates, said bodies, pins and plates coacting to impart arcuate movement to the frame and modeling body along two paths when the frame is moved vertically.

12. A grinding machine for modeling cusps. for artificial posterior teeth, comprising a rotary grinding disk disposed in a vertical plane, a table mounted for oscillation on a vertical pivot in said plane, a pair of standards supported vertically upon the table upon opposite sides of said plane, a series of guides extending. longitudinally of and carried by each standard above the table, each series being divided into a group having longitudinally convex edges and a group having lonigitudinally concave edges, a frame adapted to extend through said plane and across said standards, a, guide contacting body at each end of the frame, a guide contacting pin at each end of the frame and extending transversely thereof to position across a guide, saidpins being spaced to position between the standards, a modeling body support secured to said frame to position adjacent the edge of said disk when said pins and bodies are in contact with their respective guides, said i modeling body supporting means being joined to the frame for oscillation on a horizontal axis lying in the plane of the disk, and means for moving the modeling body supporting means along an arcuate path extending across said plane, the

guides engaged by said bodies being of duplicate Y character and the guides engaged by said pins being of opposite character whereby ver-tical movement of the frame will impart thereto vertical arcuate movement along two paths.

13. A grinding machine for modeling cusps for articial posterior teeth, comprising a rotaryl y grinding disk disposed in a vertical plane, a table mounted for oscillation on a vertical pivot in said plane, a pair of standards supported vertically upon the table upon opposite sides of said plane, a series of guides extending longitudinally of and carried by each standard above the table,

-each series being divided into a group having longitudinallyjconvex edges and a. group having longitudinally concave edges, a frame adapted to extend through said plane and across said standards, a guide contacting body at each end of the frame, a guide contacting pin at each end of the frame and extending transversely thereof to position across a guide, said pins being spaced to position between the standards, a modeling body support secured to said frame to position adjacent the edge of said disk when said pins and bodies are in contact With their respective guides, said modeling body supporting means being joined to the frame for oscillation on a horizontal axis lying in the plane of the disk, means for moving the modeling body supporting means along an arcuate path extending across said plane, the guides engaged by said bodies being of duplicate character and the guides engaged by said pins being of opposite characterv whereby vertical movement of the frame will impart thereto Vertical arcuate movement along two paths, said standards being mounted for oscillation, and means for effecting the simultaneous oscillation of the standards to change the characters of the guides engaged by said bodies and pins upon oscillation of the table on its pivotal axis.

14. A grinding machine for modeling cusps for articial posterior teeth, comprising a grinding disk, a table oscillatably mounted on a pivotal axis arranged in the plane of the disk, means for shifting said table along two perpendicularly related horizontal paths, a frame, means for supporting a modeling body on the frame, the frame being adapted to be manually held in position for contacting the periphery of the disk With the modeling body, means for shifting the modeling body supporting means along an arcuate path extending across the plane of said disk, indexing means for noting the position of the modeling body supporting means. in said arcuate path With respect to the disk, and guiding and centering means operatively coupling the frame with the table which is so constructed and arranged that upon manual movement of the frame vertically the frame will be given a movement along two opposite arcuate paths.

15. A grinding machine for modeling cusps for articial posterior teeth, comprising a grinding disk, a table oscillatably mounted on a pivotal axis arranged in the plane of the disk, means for shifting said table along two perpendicularly related horizontal paths, a frame, means for supporting a modeling body on the frame, the frame being adapted to be manually held in position for contacting the periphery of the disk with the modeling body, means for shifting the modeling body supporting means along an arcuate path extending across the plane' of said disk, indexing means for noting the position of the modeling body supporting means in said arcuate path with respect to the disk, guiding and centering means operatively coupling the frame with the table which is so constructed and arranged that upon manual movement of the frame vertically the frame will be given a movement along two opposite arcuate paths, and means for oscillating the modeling body supported means on the frame on an axis lying in and paralleling the plane of the disk.

WALTER J. WILSON. 

